Weilian Guo

CMOS-NDR transistor

In this paper, a novel device - MOS-NDR transistor is proposed and fabricated which is composed of four N-channel metal-oxide-semiconductor field effect-transistor (NMOS) devices. This MOS-NDR transistor could exhibit the negative differential resistance (NDR) characteristics similar to the conventional NDR device such as compound material based RTD (resonant tunneling diode) in the current-voltage characteristics by suitably modulating the MOS parameters, at the same time it could realize good modulation effect by the third terminal and has advantages of low working voltage (peak voltage Vp=0.7 V) and high PVCR (Peak to Valley Current Ratio) (nearly 10:1). The design and fabrication of this device are completely compatible with the standard 0.35 ¿m CMOS process, thus can considerably extend the functions of the CMOS circuits into new scope.

Monostable–Bistable Transition Logic Element Formed by Tunneling Real-Space Transfer Transistors With Negative Differential Resistance

We demonstrate three-terminal λ-type negative differential resistance (NDR) tunneling real-space transfer transistors (TRSTT) with InGaAs and a δ-doped GaAs dual-channel structure on a (100) GaAs substrate. The NDR mechanism is attributed to the electron tunneling transfer from a high-mobility InGaAs channel to a low-mobility δ-doped GaAs channel, as well as to a gate electrode through a Schottky cap layer. The maximum of the peak-to-valley current ratio and the transconductance of the peak current density (<i>g</i>_m = Δ<i>J</i>_P/Δ<i>V</i>_GS) reach 3.3 and 72 mS/mm, respectively. The invert operation of MOBILE is realized by employing two TRSTTs connected in series at room temperature.

The study on nonlinear bifurcation dynamics of a semiconductor ring laser

Based on dynamics models of the electronic bi-stable behavior in a semiconductor ring laser and using the methods of the modern nonlinear dynamics, the stability and bifuraction behavior in a semiconductor ring laser are analyzed and calculated in this paper. The calculated results show that the ring laser can undergoes the Hopf bifurcation by changing pump parameters which can lead the complex nonlinear movement such as limit cycle and Chaos. The effects of backscatter parameters on the operation regions are also calculated The calculated results show that the change of backscatter parameter can result different dynamics behaviors including bifurcation. At last the theoretical result is compared with experiment. The device process and structure is described and the experiment result agree with our theory.

Fabrication and DC current-voltage characteristics of real space transfer transistor with dual-quantum-well channel

We reported the standard ¿¿¿ shape negative differential resistance as well as a level and smooth valley region in real space transfer transistor (RSTT) with dual-quantum-well channel, which are formed by ¿-doping GaAs quantum-well and InGaAs/GaAs heterojunction quantum-well. The highest peak-to-valley current ratio (PVCR) of RSTT reaches 4 at room temperature. The highest peak current density transconductance (¿JP/¿VGS) is 130 ms/mm, which demonstrates the control ability of gate to JP. The mechanism of obvious NDR of RSTT can be explained that the hot electron in the InGaAs U-shaped quantum-well channel transfers into V-shaped ¿-doping GaAs quantum-well channel, and the hot electron transfers into gate electrode from V-shaped ¿-doping GaAs quantum-well channel. This novel NDR device would be expected to applied in NDR circuits to instead of RTD+HEMT.

The equivalent circuit model on the room temperature electroluminescence from forward biased pin silicon diode

As the length scale of the devices decreases, electrons will spend increasingly more of their time in the connections between components; this interconnectivity problem could restrict further increases in computer chip processing power and speed. Considerable effort is therefore being expended on the development of efficient silicon light-emitting devices compatible with silicon based integrated circuit technology. Here, we describe the electrical and optical properties of Silicon positive intrinsic negative (pin) structure diode that operates at room temperature. The voltage-current and electroluminescence (EL) property are measured at room temperature for a silicon pin diode under forward biased current. The optical spectral response of the system at 700nm indicates that the emitting light source has low optical loss in Silicon. So the LED is suitable for Silicon optoelectronic interconnection system.[1][2] The rate-equation model for free carriers on light-emitting pin structure and the equivalent circuit model based on it have been presented. We have developed a way to calculate the model parameters by comparison with experimental results. This parameter extraction way can be fully accomplished automatically by using MATHCAD program and the equivalent circuit model is simulated by using HSPICE program respectively. The results of both experiment and simulation results are good agreement with each other.

Photocontrolled Terahertz Amplified Modulator via Plasma Wave Excitation in ORTD-Gated HEMTs

This paper theoretically explores photocontrolled terahertz amplified modulator in electron plasma wave optically switched resonant tunneling diode (ORTD) gate high-electron mobility transistor. We present a developed distributed circuit model based on the Khmyrova model. Photoexcitation causes ORTD operating state between negative differential conductivity and positive differential conductivity, which power gain of the device can be control by photoexcitation. Numerical and analytical results show that photoexcitation enabling amplified modulator can realize much larger modulation depth (>95%) than what has been reported in photocontrolled modulator. Our results show the potential of this device in several fields of terahertz technology, such as photocontrolled modulator, mixer, and other two port networks.

High Optical Power Density Forward-Biased Silicon LEDs in Standard CMOS Process

This letter presents three low-operating-voltage silicon-based light-emitting devices (Si-LEDs) designed and made in a commercial standard 0.18-μm CMOS process without any modification. The Si-LEDs with a new threeterminal and wedge-shaped forward-biased carrier-injection-type p⁺-n junction structure, have high optical powers. The output power increases by two orders of magnitude up to 1.78 μW without saturation when the forward current is increased from 20 mA to 200 mA. The light-emitting area is the n-type drift region between the n⁺ region and p⁺ region. When the forward current increases to 200 mA, the optical power density exceeds 30 nW · μm^-2 the power conversion efficiency and external quantum efficiency are ~2 × 10^-6 and 8.3 × 10^-6, respectively, higher than all other forward-biased Si-LEDs previously reported to have used CMOS processes without any modification.

Effects of Structure Parameters on Temperature Characteristics of Multiple Quantum Well Ring Laser

Due to the potential application in all-optical signal processing, semiconductor ring laser (SRL) has become one of research hotspots in the present. In this paper, an equivalent SRL was modeled utilizing a numerical device simulator (ATLAS), and the effects of structure parameter on the temperature characteristics of multiple quantum well SRL were simulated and analyzed with temperature range from 260K to 460K. The simulation results indicated that an optimal quantum well structure with well width around 20nm and well number of five existed for the lowest threshold current density. And the ring radius has little effect on the temperature characteristics of differential quantum efficiency and lasing wavelength. Keywordstemperature characteristics; semiconductor ring laser; multiple quantum well; gallium arsenide

Optical bistability in InP/InAlGaAs multi-quantum-well semiconductor ring lasers

We demonstrate optical bistability in InP/InAlGaAs multi-quantum well(MQW) semiconductor ring lasers(SRL) which are fabricated by the use of inductively coupled plasma reactive ion etching (ICP-RIE) and can be used in a multi-ring to achieve all-optical storage. Unlike other international reports, the observed optical bistability has unidirectional regime started directly from the threshold, skip the first two regimes and greatly reduce the injection current required in applications. The device described in this article achieves threshold current 56mA which is quite low compared to other reported devices, and some analysis and experiments on the etching depth have been done.

The design, fabrication and characterization of GaAs-based RTT with groove and self-aligned Schottky gate structure

In this paper, the design of material structure and device structure , fabrication processing and characterization on GaAs based Resonant Tunneling Transistor (RTT) with groove and self-aligned gate structure have been described completely and systematically .The experimental results measured from our fabricated RTT show that : the maximum value of Peak to Valley Current Ratio (PVCR) is 46, the transconductance gm is in a range of 1.3~8.0 ms, the cutoff frequency fTgm and speed index S are 1.59 GHz and 13.5 ps/V respectively .